The present invention is directed to power converters, for example motor drives, used to convert electrical energy from one form to another. More specifically, the present invention provides a method and apparatus for mounting the power converter.
As is known to those skilled in the art, power converters, such as motor drives, are commonly mounted within an industrial enclosure. Industrial enclosures may be configured according to many specifications such as those established by the National Electrical Manufacturers Association (NEMA), the Underwriters Laboratories (UL), or the International Electrotechnical Commission (IEC). These classifications define a series of increasing levels of protection that the enclosures must provide to personnel working around the enclosure or to the equipment contained within the enclosure. NEMA type 4 enclosures, for example, require the enclosure to be constructed for either indoor or outdoor use and to provide a degree of protection to personnel against access to hazardous parts, to provide a degree of protection of the equipment inside the enclosure against ingress of dust or water, and that will be undamaged by the external formation of ice on the enclosure. NEMA type 4X enclosures further require a level of protection against corrosion.
The environments in which the power converter and enclosure are installed typically dictate the level of protection required. The enclosures are often purchased according to the desired level of protection. The enclosures may be made of different materials, utilize different closing members, or different sealing members according to the specified level of protection. In most instances, a power converter may be mounted entirely inside the enclosure, thereby maintaining the original level of protection for which the enclosure was designed. Optionally, a power converter may need to extend outside the enclosure. For example, due to the size of the converter or due to cooling requirements, a heat sink connected to the power converter may extend through one surface of the enclosure. In order for the enclosure to retain its rated level of protection, the hole through which the power converter extends must be sealed to meet the same level of protection as required by the enclosure.
In the past, many converters configured for such an application included a flange integrally formed with the converter housing or provided an add-on flange that sealingly cooperated with the converter and the surrounding enclosure. However, providing a converter with an integral flange increases the cost associated with such converters. Further, different housings must be manufactured and supplied for each converter according to the environment in which it is to be installed.
Providing an add-on flange has also typically incurred various disadvantages. Existing add-on flanges have commonly been secured to the converter and the enclosure in such a manner that the converter can no longer be removed from the enclosure independently of the flange. Such an arrangement complicates the efforts associated with servicing the respective converters. Furthermore, removing the flange to service the converter increases the potential for leaks to form between the converter and the flange when the flange is reinstalled in the enclosure. Such flanges are susceptible to overly complicated mounting and integration assemblies, poor or inadequate sealing, assembly prior to installation of the converter, and cost increases with respect to base model assemblies.
Therefore, there is a need to provide a converter mounting assembly that can provide a generally sealed mounting of the converter in accordance with different enclosure specifications, for example, NEMA Type 4/4X, NEMA Type 12, UL Type 12, IP5X, and IP6X applications. The mounting assembly can provide multiple mounting protocols, is simple to integrate with existing product platforms, and minimally affects the cost associated with providing a converter useable in a variety of other types of applications.